Given its past, Germany has some very strict laws against hate speech—and Facebook has run afoul of them, says a petition in Munich. According to the German magazine Der Spiegel, the Munich prosecutor’s office has begun a preliminary investigation into a criminal complaint against Facebook executives Mark Zuckerberg and Sheryl Sandberg, and lobbyists Richard Allan and Eva-Maria Kirschsieper.

Facebook has been under pressure from German authorities for more than a year for not promptly removing hate speech and calls to violence. The company isn’t expected to police every post, but it is required under German law to remove any offending material that is reported to it. The complaint says it has done a poor job of this, tolerating incitements to murder, threats of violence, and Holocaust denial.

Unlike the U.S., which has broad protections for free speech, certain sentiments are strictly verboten in Germany. The law prohibits Volksverhetzung—incitement of the people—toward violence or even an assault on the “human dignity” of any national, racial, ethnic, or religious group. Glorifying the Nazis is also illegal, punishable by up to five years in prison. It’s not clear how far the Munich action can go, however. A complaint in Hamburg against Zuckerberg, Sandberg, and other execs came to nothing earlier this year because it was found that they are outside the authority of German law.